1. Field of the Invention
The present invention relates to an expansion tube joint and an assembling method thereof.
2. Description of the Related Art
Expansion tube joints are widely used in water pipes and the like. There is a conventional expansion tube joint as shown in FIG. 10. This expansion tube joint comprises a first cylindrical body 1, and a second cylindrical body 2 inserted into the first cylindrical body 1 along the axis X thereof A T-shaped rubber ring 3 (corresponding to a seal member) is provided between the first and second cylindrical bodies 1 and 2 (between an inner periphery of the first cylindrical body 1 and an outer periphery of the second cylindrical body 2). The second cylindrical body 2 is extendable relative to the first cylindrical body 1, and the relative movement range in the axial direction X is limited by a lock mechanism in the expanding and contracting direction.
The lock mechanism will be explained. A stopper in the contracting direction comprises an inner wall projection 1a of the first cylindrical body 1, and an outer wall projection 2a of the second cylindrical body 2. A stopper in the extending direction comprises a stopper ring 4 mounted to an insertion port of the first cylindrical body 1 and the outer wall projection 2a. That is, the lock mechanism is formed closer to the insertion port of the first cylindrical body 1, and the seal member is disposed deeper than the lock mechanism.
With this structure, in a state where the second cylindrical body 2 is inserted into the first cylindrical body 1 deepest, the second cylindrical body 2 must have extra length L from the T-shaped rubber ring 3. The reason why the second cylindrical body 2 must have the extra length L is that when the second cylindrical body 2 moves in the extending direction (rightward in FIG. 10) from a state shown in FIG. 10, the seal function by the T-shaped rubber ring 3 must be secured,
Since the length of the second cylindrical body 2 must be secure, the length of the expansion tube joint in the axial direction becomes long, the weight is increased, and the size is also increased. Therefore, there is a problem that costs for producing, storing and transferring the expansion tube joint are increased.
The present invention has been accomplished in view of the above circumstances, and it is an object of the present invention to provide a technique capable of shortening the length of the second cylindrical body as compared with the prior art, and capable of reducing the weight and size of the expansion tube joint to reduce the costs.